Mark Galassi is a physicist, computer scientist, and contributor to the free and open-source software movement.

[4] Galassi works in the Space Science and Applications group at the Los Alamos National Laboratory as a research scientist.

[12] He was also an early contributor to GNOME,[13] and designed and led development of the Dominion world simulation game.

[14] He has served on the board of directors of the Software Freedom Conservancy[15] from its inception until the present time.

[16] Galassi has been training students since the 1980s,[17][18] teaching them in research methods, with emphasis on using only free/open-source software tools.